Hello and welcome to pc! I'm surprised after your well put backstory that your question is if it is garden variety cheating. Yes, I suppose it is only sexting with strangers. It gives you more of a jolly because you are doing something naughty and not even really a sexual thrill.

Plus your wife threatened to end your marriage, but she just had a baby with you, so she will probably put up with this behavior until your daughter gets a little older.

You are sexting because of deeper resentment issues.